A. Field of Invention
The present invention relates generally to methods and apparatus for dispensing small volumes of fluid and more particularly to a new and improved method of dispensing very small volumes of fluid by means of an apparatus comprised of known and available fluid control components in a novel arrangement.
B. Description of Related Art
In systems requiring a means of dispensing extremely small amounts of fluid, limitations of size, external plumbing, and economics of precision metering equipment limit the usefulness of common solutions. For example, direct use of a simple dispensing pump to push a small volume out a nozzle requires the pump to perform a very limited operation. For example, a simple displacement pump must operate either an extremely small physical component or to move a component through a very short or small range of motion to achieve a volume differential small enough to result in the accurate dispensing of a small volume of fluid. In many applications in which such small volumes of fluid are desired, the allowable margin of error may be difficult to achieve due to normal pump operation variances. One method of avoiding such error is to supply a constant pneumatic pressure to a fluid system and interpose a fast acting flow control valve between the pressure source and a nozzle, whereby opening the valve for a brief time allows limited flow to a nozzle and thus dispensing a small volume of fluid. In some applications however, supplying pneumatic pressure to an array of nozzles can be cumbersome and may not allow use in applications where space is limited. Therefore, there is a need for a compact and self contained means for dispensing minute volumes of fluid, and a method of utilizing existing devises to achieve said function is desirable and needed.